Addition of butylamine to a solution of colloidal CdSe nanoparticles (NPs)
caused a decrease in fluorescence intensity, with no effect on the picoseco
nd bleach recovery of the exciton formation or on the luminescence dynamics
. The relative fluorescence quantum yield was found to decrease with increa
sing butylamine concentration and to level off at high concentrations, but
the fluorescence lifetimes were not influenced. The nonlinear concentration
dependence of the fluorescence quantum yield did not follow the Stern-Volm
er equation. This is in agreement with the observation that the CdSe lumine
scence lifetime was not affected by the addition of butylamine. A mechanism
is proposed in which the emission observed in CdSe is assumed to result fr
om the combination of surface-trapped electrons and holes. n-Butylamine occ
upies hole sites, thus blocking the recombination process, which results in
decreasing the density of luminescent centers. These results will be discu
ssed in terms of the nature of the binding sites of the amine on the nanopa
rticle surface.